Mr Stoltenberg, who will visit South Korea and Japan in the coming weeks as a show of support, stressed that Washington had the right to defend itself and its allies, but called for greater diplomatic efforts.
His comments came as Pyongyang made fresh threats to attack Guam with a 'salvo of missiles' in response to a U.S. aviation exercise over the Korean peninsula.
Warning: NATO Secretary General Jens Stoltenberg said that while the U.S. have every right to defend itself, a war with North Korea would have 'devastating consequences'
Kim Jong-Un 's government warned that a joint exercise with Japan and South Korea has 'hardened our determination that the U.S. should be tamed with fire'.
In a statement published in North Korean state media, Pyongyang said the military drills 'lets us take our hand closer to the 'trigger' for taking the toughest countermeasure'.
Mr Stoltenberg, former Prime Minister of Norway, said in an interview at NATO HQ in Brussels that he did not think anybody wants a war.
'The use of military force will have devastating consequences, I think nobody really wants that, therefore we need to continue to push for a negotiated solution.
Ready to tweet: President Trump met his national security team on Tuesday and discussed a 'range of options' to respond to Pyongyang's repeated recent nuclear and ballistic missile tests
A US Pacific Command B-1B Lancer takes off from Guam on Tuesday as part of a combined training mission with Japanese and South Korean fighter aircraft around North Korea
'The US has the right to defend itself, to defend its allies, but at same time I am absolutely certain no one wants a military solution, so we still see a united effort to try to step up the pressure against North Korea.'
Trump met his national security team on Tuesday and discussed a 'range of options' to respond to Pyongyang's repeated recent nuclear and ballistic missile tests.
The meeting came days after Trump, who last month threatened to 'destroy' North Korea, said on Twitter that years of talks with Pyongyang had achieved nothing and 'only one thing will work'.
The United States and South Korea will kick off a major navy drill in the Sea of Japan and the Yellow Sea in a show of force against the North next week and there has been a flurry of military hardware movement in the region in recent days.
Warning: North Korean leader Kim Jong-Un warned that a joint exercise with Japan and South Korea had 'hardened our determination that the U.S. should be tamed with fire'
Earlier this week two supersonic US heavy bombers flew over the Korean peninsula, staging the first night-time joint aviation exercises with Japan and South Korea, the latest in a series of flyovers.
Stoltenberg stressed that NATO was 'not planning any military presence in that part of the world' and no such request had been received from Tokyo or Seoul.
But the growing range and accuracy seen in the North's missile tests has prompted the 29-nation alliance to review its missile defence system, which has been partially operational from a base in Romania since last year.
'Our experts are working on technology, on how to improve our systems,' Stoltenberg said.